Androstanediol glucuronide isomers in normal men and women and in men infused with labeled dihydrotestosterone

3α-Androstanediol glucuronide (Adiol G) is a major metabolite of dihydrotestosterone (DHT). Adiol G actually represents 2 different compounds, since the glucuronide can be conjugated at the 3-carbon position (Adiol 3-G) or at the 17-carbon position (Adiol 17-G). To determine which glucuronide represents the predominant physiological DHT metabolite and which isomer is the major circulating form, we developed a RIA to directly measure Adiol 3-G in serum extracts. In 10 normal men, mean serum Adiol 3-G and total Adiol G levels were 4.44 ± 0.49 (±se>) nmol/L (208 ± 23 ng/dL) and 27.9 ± 2.8 nmol/L (1310 ± 129 ng/dL), respectively (13.9 ± 3.0% of Adiol G was Adiol 3-G). In 10 normal women sampled during the early follicular phase, mean serum Adiol 3-G and total Adiol G levels were 2.64 ± 0.64 nmol/L (124 ± 30 ng/dL) and 14.9 ± 1.5 nmol/L (697 ± 69 ng/dL), respectively (17.4 ± 3.6% of Adiol G was Adiol 3-G). In 4 normal men infused for 8 h with tritiated DHT, 17.4 ± 3.4% of the resulting tritiated Adiol G was Adiol 3-G. These results indicate that Adiol 17-G is the predominant circulating form of Adiol G in normal men and women and that it is also the major Adiol G isomer derived from DHT.